Process for Preparing Amine-Modified Polyester Resins with Improved Melt Flow

ABSTRACT

The invention is directed to a process for preparing a linear or branched amine-modified thermoplastic resin with high flowability using as starting materials a linear or branched polyester and a primary or secondary aliphatic amine. The process does not require that the amine and polyester be combined in a liquid organic solvent during the process, and can be performed readily at ambient pressure. The amine-modified resins can be extruded and pelletized using normal operating conditions, making this process a versatile option for achieving a wide variety of viscosities in a simple, low cost, continuous operation.

BACKGROUND OF THE INVENTION

The invention relates to a process for preparing amine-modifiedpolyester resins with improved melt flow.

Polyesters and copolyesters, as well as their blends with otherthermoplastics, are used to make a range of products that includesinjection molded parts, films, blow-molded goods, and pultruded sheets.These articles are used in automotive, electrical and electronicapplications. The mechanical strength, electrical insulation and easyprocessability are some of the key characteristics of polyesters whichenable their use in these applications. The current industrial trend istoward the fabrication of parts, with complicated and fine designs, withsmall flow cross-sectional areas where the fluidity of conventionalpolyesters has been found inadequate.

To address the demanding requirements of high melt flowability, apolyester resin can be replaced by another polyester resin having lowerviscosity. Thus there exists a need to prepare a wide variety of highflow polyester resins in a simple, low cost manner that can be appliedto both large and small scale continuous production. Further, theprocess should be environmentally friendly using no solvent.Furthermore, the process should be accomplished without the need forlarge scale chemical plant construction or capital investment. In otherinstances there is a need to convert high viscosity polyestercompositions into lower viscosity compositions through a simple low costmelt process.

U.S. Pat. Nos. 7,825,176, 7,405,250, and 7,405,249 disclose polyestercompositions with high flowability. The compositions comprise apolyester and an alcohol that acts as a flow enhancer. A need remains,however, for processes to make amide functionalized polyestercompositions with high flowability that rely on non-alcoholic flowenhancers.

SUMMARY OF THE INVENTION

These and other needs are met by the present invention, which isdirected to a process for preparing amine-modified polyester resins by asimple, inexpensive solvent-free process. Specifically, the invention isdirected to a solvent-free process for preparing an amine-modifiedthermoplastic polyester resin by mixing a melted polyester of Formula 1,shown below,

with a melted amine, having the formula NHR¹R², thereby forming anamine-modified thermoplastic polyester resin characterized by one orboth of the following properties:

(i) the resin comprises 0.01 to 5 weight percent of the amine; and

(ii) the ratio of the melt flow of the resin compared to the unmodifiedpolyester of Formula, as measured according to ASTM D1238, is at least1.05:1.

For the polyester of Formula 1, each T is independently a divalent C₆₋₁₀aromatic group derived from a dicarboxylic acid or a chemical equivalentthereof. Also, each D is independently a divalent C_(m) alkylene groupderived from a dihydroxy compound or a chemical equivalent thereof.Additionally, m is from 25 to 1000.

For the amine of the present invention, R¹ is C₆-C₃₆ alkyl; R² isselected from the group consisting of hydrogen, C₁-C₃₆ alkyl, C₁-C₃₆alkylene-aryl, C₁-C₃₆ alkylene-heteroaryl, C₁-C₃₆ alkylene-cycloalkyl,C₁-C₃₆ alkylene-heterocycloalkyl; and NHR¹R² contains at least 10carbons.

In another aspect, the invention is directed to compositions comprisingthe resins described herein, as well as to articles prepared by theprocess of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

All cited patents, patent applications, and other references areincorporated herein by reference in their entirety. However, if a termin the present application contradicts or conflicts with a term in theincorporated reference, the term from the present application takesprecedence over the conflicting term from the incorporated reference.All ranges disclosed herein are inclusive of the endpoints, and theendpoints are independently combinable with each other. The use of theterms “a” and “an” and “the” and similar referents in the context ofdescribing the invention (especially in the context of claims) are to beconstrued to cover both the singular and the plural, unless otherwiseindicated herein or clearly contradicted by context. Further, it shouldfurther be noted that the terms “first,” “second,” and the like hereindo not denote any order, quantity, or importance, but rather are used todistinguish one element from another. The modifier “about” used inconnection with a quantity is inclusive of the stated value and has themeaning dictated by the context (that is, it includes the degree oferror associated with measurement of the particular quantity).

Process of the Invention

As provided above, the invention is directed to a process for preparinga linear or branched amine-modified polyester resin using a linear orbranched polyester and an amine, NHR¹R², as starting materials. In theprocess of the present invention, melted polyester is mixed with meltedamine to form an amine-modified polyester resin. The polyester can bemelted, by heating to a temperature at or above its melting point,before mixing with the amine, concurrent with mixing with the amine,after initially mixing with the amine, or a combination thereof.

The term “melted amine” means an amine that is in its liquid state atroom temperature or which requires heating to melt. In the presentinvention, the amine can be melted before mixing with the polyester,concurrent with mixing with the polyester, after initially mixing withthe polyester, or a combination thereof.

However, to form the amine-modified polyester, of the present invention,mixing of melted polyester and melted amine must occur.

“Solvent-free” as used herein, means free of a liquid that solubilizesthe polyester, the amine, or both polyester and amine, prior to, during,or subsequent to the process of mixing the components to form theamine-modified resin. Solvent-free means that organic or aqueoussolvents, if present at all, are present only in trace or residualquantities. If an organic liquid solvent is present in the mixture, itis typically a residual solvent, such as chlorobenzene, dichlorobenzene,toluene, cresol, phenol, chloroethylenes or the like, that was used inan earlier processing or manufacturing steps, and is at a concentrationof 1000 ppm or less and more preferably of 500 ppm or less. Typically,such residual solvents have a molecular weight of less than 200 and aboiling point at ambient pressure of 200° C. or lower. “Ambientpressure” means the atmospheric pressure where the resin is beingmanufactured, which is typically measured as barometric pressure.

In addition, both the mixing and melting steps of the resin process arereadily performed at ambient pressure with no vacuum applied to preventthe amine from volatilizing before reacting.

The materials used in the process of the present invention includepolyesters, a primary or a secondary aliphatic amine or mixture thereof,and optional additives.

In one embodiment, the polyester is a linear polyester having repeatingstructural units of Formula 1:

wherein, for a single repeating unit, the value of m is 1. Further, theamine is NHR¹R², wherein at least one of R¹ and R² is C₁₀₋₃₆ alkyl andthe other of R¹ and R² is selected from the group consisting ofhydrogen, C₁-C₃₆ alkyl, C₁-C₃₆ alkylene-aryl, C₁-C₃₆alkylene-heteroaryl, C₁-C₃₆ alkylene-cycloalkyl, C₁-C₃₆alkylene-heterocycloalkyl; and the resulting resin is a linear resin ofFormula 2:

wherein:

each T is independently a divalent C₆₋₁₀ aromatic group derived from adicarboxylic acid or a chemical equivalent thereof;

each D is independently a divalent C₂₋₈ alkylene group derived from adihydroxy compound or a chemical equivalent thereof;

R¹ is C₆₋₃₆ alky and R² is selected from the group consisting ofhydrogen, C₁-C₃₆ alkyl, C₁-C₃₆ alkylene-aryl, C₁-C₃₆alkylene-heteroaryl, C₁-C₃₆ alkylene-cycloalkyl, and C₁-C₃₆alkylene-heterocycloalkyl;

m and n vary from 25 to 1000; and

n is less than m.

In other embodiments, the ingredients of the composition of the presentinvention may additionally optionally comprise fillers, reinforcement,colorants additives, or combinations thereof.

The composition ingredients of these and other embodiments are describedin greater detail in the following paragraphs.

Polyester

The polyesters used in the process and composition disclosed herein arelinear or branched thermoplastic polyesters having repeating structuralunits of Formula 1.

In one embodiment, each T group is the same and each D group is thesame.

Alternately, copolyesters containing a combination of different T and/orD groups can also be used.

Chemical equivalents of diacids include the corresponding esters, alkylesters, e.g., C₁₋₃ dialkyl esters, diaryl esters, anhydrides, salts,acid chlorides, acid bromides, and the like.

Chemical equivalents of dihydroxy compounds include the correspondingesters, such as C₁₋₃ dialkyl esters, diaryl esters, and the like. Thepolyesters can be branched or linear.

Examples of C₆₋₁₄ aromatic dicarboxylic acids that can be used toprepare the polyesters include isophthalic acid, terephthalic acid,1,2-di(p-carboxyphenyl)ethane, 4,4′-dicarboxydiphenyl ether,4,4′-bisbenzoic acid, and the like, and 1,4- or 1,5-naphthalenedicarboxylic acids and the like. A combination of isophthalic acid andterephthalic acid can be used, wherein the weight ratio of isophthalicacid to terephthalic acid is 91:9 to 2:98, specifically 25:75 to 2:98.In some instances 50 percent or more of the ester linkages in Formula 1are terephthalate ester linkages.

Exemplary diols useful in the preparation of the polyesters include C₂₄aliphatic diols such as ethylene glycol, 1,2-propylene glycol,1,3-propylene glycol, 1,4-butane diol, 1,2-butylene diol, 1,4-but-2-enediol, diethylene glycol, cyclohexane dimethanol, and the like. In oneembodiment, the diol is ethylene and/or 1,4-butylene diol. In anotherembodiment, the diol is 1,4-butylene diol. In still another embodiment,the diol is ethylene glycol with small amounts (0.5 to 5.0 percent) ofdiethylene glycol.

In some embodiments, each T in the resin of Formula 1 is independentlyphenyl or naphthyl, and each D in the resin of Formula 1 isindependently selected from the group consisting of ethylene, propylene,butylene, and dimethylene cyclohexene.

Specific exemplary polyesters include poly(ethylene terephthalate)(PET), poly(1,4-butylene terephthalate) (PBT), poly(ethylenenaphthalate) (PEN), poly(butylene naphthalate) (PBN), andpoly(1,3-propylene terephthalate) (PPT), poly(cyclohexylenedimethyleneterephthalate) (PCT) or blends thereof. In one embodiment, the polyesteris PET, PBT or a mixture thereof.

In some embodiments, the polyester of Formula 1 is a post-consumer(recycled) polyester, such as recycled PET or similar recycled resins.Such recycled resins are commercially available from a variety ofsources such as bottles, films, and fibers. In one instance postconsumer PET bottles with a diethylene glycol (DEG) content of 0.5 to2.5 mole percent and 10 to 500 ppm of a metal selected from the groupconsisting of Ti, Sb, Sn, Zn, Ge, Zr, Co or mixtures thereof arepreferred.

In still another specific embodiment, the polyester is PBT with a weightaverage molecular weight (Mw) of 10,000 to 50,000. It is to beunderstood that such terephthalate-based polyesters can include amountsof aliphatic diacids or isophthalate esters as well. Mixtures ofpolyesters of different type and/or different molecular weights can alsobe employed. In some embodiments, 50 percent or more of the esterlinkages in formula A are terephthalate ester linkages.

Typically, the polyester will further contain 10 to 500 ppm of a metalcatalyst residue wherein the metal is selected from the group consistingof at least one: Ti, Sb, Sn, Zn, Ge, Zr, and Co. The polyester mayfurther comprise 10 to 200 ppm of a phosphorous containing compound suchas acidic phosphorus species used as a catalyst quencher.

The polyesters of formula 1 can have any end group configuration. Inmost instances the end groups will be hydroxy, carboxylic acid or esterend groups. In some instances, the polyester will have a carboxylic acid(COOH) end group content of from 15 to 40 meq/Kg.

Amine

The amine used in the process and composition disclosed and claimedherein is a primary or secondary aliphatic amine or any mixture thereof,thermally stable at polyester melt processing temperatures, above about200° C. and more specifically above about 250° C. The amine of theprocess and composition disclosed herein typically has a boiling pointthat is 200° C. or higher at ambient pressure and a carbon to nitrogenratio of 10:1 to 36:1, and thus a total number of carbons in R¹ and R²combined is from 10 to 36 carbons.

Exemplary amines are primary alkyl amine such as stearyl amine, decylamine, dodecyl amine, tetradecyl amine, 3-methyl-1-octyl amine,3-ethyl-hexyl amine, 4-phenyl butyl amine, 2,7-diphenyl heptyl amine, 1methyl-3-phenyl amine and the like. In some instances the primary aminewill be a C₁₀-C₂₀ alkyl amine.

The primary or secondary aliphatic amine can be combined in the meltwith polyester resins at from 0.01 to 5 weight percent of the mixture.Preferably, the composition will employ the amine in an amount of from0.05 to about 2.5 weight percent and more preferably, in an amount offrom 0.1 to about 1.0 weight percent of the amine. In some instances theamine will be a low color amine, for instance with a yellowness index ofless than 10.

Filler

A filler or reinforcement agent may also be added to the amine modifiedpolyester resin disclosed herein. In some embodiments, the filler isselected from the group consisting of fiber glass, carbon fibers,ceramic fibers, talc, clay, mica, wollastonite, silica, quartz, alumina,barium sulfate, carbon, graphite, metal oxides, glass beads, glassflakes, milled glass and any combination thereof. Fillers can also benano fillers such as nano clay and carbon nanotubes. Effective amountsof the filler vary widely, but they are usually present in an amount ofless than or equal to 1 to 60 weight percent, based on the total weightof the composition.

In some embodiments, the filler is glass fiber. In one embodiment, theglass fibers that are used are relatively soda free. Fibrous glassfilaments comprised of borosilicate glass, also known as “E” glass, areoften preferred. Glass fiber is added to the composition to increase theflexural modulus and strength. The glass filaments can be made bystandard processes, e.g., by steam or air blowing, flame blowing andmechanical pulling. The preferred filaments for plastic reinforcementare made by mechanical pulling in various diameters. The fibers can alsobe bundled and chopped for easier handling. The fibers can be furthertreated with coupling agents and sizing. Exemplary coupling agents areamine or epoxy functional alkoxy silanes. In some embodiments the glassfiber of a 9 to 20 micron diameter is present at 10 to 40 weightpercent.

The glass fibers may be blended first with the other ingredients andthen fed to an extruder and the extrudate cut into pellets, or, in apreferred embodiment, they may be separately fed to the feed hopper ofan extruder. The glass fibers may be fed downstream in the extruder tominimize attrition of the glass. The pellets so prepared when cuttingthe extrudate may be one-fourth inch long or less. Such pellets containfinely divided uniformly dispersed glass fibers in the composition. Thedispersed glass fibers are reduced in length as a result of the shearingaction on the chopped glass strands in the extruder barrel. This processcan also be used to make long glass reinforced modified compositionswherein the glass fiber in essentially continuous in the pellet,sometimes as long as 0.5 to 1.0 inches.

The amine compounds can be feed into the melt processing equipment, forinstance an extruder, along with the additive, for instance glass fiber,to form the modified polyester composition while mixing in the additive.In other instances the additive or fiber can be pre-compounded into thepolyester and then melt processed with the amine compound to prepare theimproved flow composition.

Additives

The resin disclosed herein can also include various other additivesordinarily incorporated with compositions of this type, with the provisothat the additives are selected so as not to significantly adverselyaffect the desired properties of the composition. Combinations ofadditives can be used. Exemplary additives include anti-oxidants, dyes,pigments, colorants, heat stabilizers, flame retardants, dripretardants, crystallization nucleators, metal salts, antistatic agents,plasticizers, lubricants, UV stabilizers, and combinations comprisingtwo or more of the foregoing additives. These additives are known in theart as are their effective levels and methods of incorporation.Effective amounts of the additives vary widely, but they are usuallypresent in an amount of less than or equal to 10 weight percent, basedon the total weight of the composition. Amounts of these additives aregenerally 0.25 weight percent to 2 weight percent, based upon the totalweight of the composition.

Exemplary antioxidant and heat stabilizer additives include, forexample, organophosphites such as tris(nonyl phenyl)phosphite,tris(2,4-di-t-butylphenyl)phosphite,bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite, distearylpentaerythritol diphosphite or the like; alkylated monophenols orpolyphenols; alkylated reaction products of polyphenols with dienes,such astetrakis[methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)]methane,or the like; butylated reaction products of para-cresol ordicyclopentadiene; alkylated hydroquinones; hydroxylated thiodiphenylethers; alkylidene-bisphenols; benzyl compounds; esters ofbeta-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid with monohydricor polyhydric alcohols; esters ofbeta-(5-tert-butyl-4-hydroxy-3-methylphenyl)-propionic acid withmonohydric or polyhydric alcohols; esters of thioalkyl or thioarylcompounds such as distearylthiopropionate, dilaurylthiopropionate,ditridecylthiodipropionate,octadecyl-3-[3,5-di-tert-butyl-4-hydroxyphenyl)propionate,pentaerythrityl-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionateor the like; amides ofbeta-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid or the like, orcombinations comprising at least one of the foregoing antioxidants.Antioxidants can be used in amounts of 0.001 to 1 weight percent, basedon the total weight of the composition.

Exemplary heat stabilizer additives include, for example,organophosphites such as triphenyl phosphite,tris-(2,6-dimethylphenyl)phosphite, tris-(mixed mono- anddi-nonylphenyl)phosphite or the like; phosphonates such asdimethylbenzene phosphonate or the like, phosphates such as trimethylphosphate, or the like, or combinations comprising at least one of theforegoing heat stabilizers.

Exemplary lubricants and mold release agents include alkyl esters forexample, pentaerythritol tetrastearate (PETS), alkyl carboxylic acidsalts, alkyl amides, such as ethylene bis-stearamide, and polyolefins,such as polyethylene.

Exemplary flame-retardant additives are present in an amount at leastsufficient to reduce the flammability of the polyester resin, preferablyto a UL94 V-0 rating. The amount will vary with the nature of the resinand with the efficiency of the additive. In general, however, the amountof additive will be from 2 to 30 percent by weight. A preferred rangewill be from about 10 to 20 percent by weight. Typical flame-retardantsinclude halogenated flame retardants such as polybromophenyl ether,brominated polystyrene, brominated BPA polyepoxide, brominated imides,or mixtures thereof. It is strongly preferred that the flame retardantadditive not chemically react with the amine additive of the invention.

Examples of other suitable flame retardants are brominated polystyrenessuch as polydibromostyrene and polytribromostyrene, decabromobiphenylethane, tetrabromobiphenyl, brominated alpha,omega-alkylene-bis-phthalimides, e.g.N,N′-ethylene-bis-tetrabromophthalimide, or brominated epoxy resins.

The halogenated flame retardants are typically used with a synergist,particularly inorganic antimony compounds. Such compounds are widelyavailable or can be made in known ways. Typical, inorganic synergistcompounds include Sb₂O₅, Sb₂S₃, sodium antimonate and the like.Especially preferred is antimony trioxide (Sb₂O₃). Synergists, such asantimony oxides, are typically used at about 0.5 to 15 by weight basedon the weight percent of resin in the final composition.

In place of halogenated flame retardants, the use of phosphorous basedflame retardants can also be envisaged. Typical phosphorous based flameretardants include organophosphates, for example triaryl phosphates,metal salts of hypophosphorous acid, metal salts of organophosphinicacid and the like. Synergists to these phosphorous based flameretardants, such as melamine cyanurates, melamine pyrophosphates andlike can also be included in the composition.

Exemplary drip retardants include fluoropolymers. The fluoropolymer maybe a fibril forming or non-fibril forming fluoropolymer. Preferably thefluoropolymer is a fibril forming polymer. In some embodimentspolytetrafluoroethylene is the preferred fluoropolymer. In someembodiments it is preferred to employ an encapsulated fluoropolymer i.e.a fluoropolymer encapsulated in a polymer as the anti-drip agent. Anencapsulated fluoropolymer can be made by polymerizing the polymer inthe presence of the fluoropolymer. Alternatively, the fluoropolymer canbe pre-blended in some manner with a second polymer, such as forexample, an aromatic polycarbonate resin or a styrene-acrylonitrileresin as in, for example, U.S. Pat. Nos. 5,521,230 and 4,579,906, toform an agglomerated material for use as an anti-drip agent. Eithermethod can be used to produce an encapsulated fluoropolymer.

The anti-drip agent, when present, comprises greater than or equal toabout 0.5 weight percent, preferably greater than or equal to about 0.1weight percent, based on the total weight of the composition. Theanti-drip agent, when present, comprises less than or equal to about 5weight percent, preferably less than or equal to about 2.5 weightpercent, and more preferably less than or equal to about 1 weightpercent, based on the total weight of the composition.

The amine modified resins prepared by the melt reaction of the aminethermoplastic polyesters may be further melt compounded with otherpolymers such as non-amine modified polyesters, polystyrene, styreneacrylonitrile (SAN), polycarbonate, polyetherimides, polyolefins andmixtures thereof. Rubber modifiers, alone or in combination with theaforementioned resins, may also be used. Exemplary rubber modifiers aremethacrylate butadiene styrene (MBS), butadiene grafted with SAN,styrene butadiene block copolymers (SBS) hydrogenated styrene butadieneblock copolymers (SEBS) as well as acrylic rubber, and acrylate styreneacrylonitrile (ASA) rubber.

Process Conditions and Resin Properties

While being held to no specific mechanism or mode of action, it isthought that the reaction that gives rise to the resins described hereinis depicted in Scheme 1, wherein polybutylene terephthalate (PBT) is thepolyester (although other polyesters can be employed).

As shown in Scheme 1, PBT B, where “P” represents a linear or branchedpolymer, is susceptible to amine attack at each ester linkage of thepolymer chain. Condensation of polyester B with the amine 3 undersuitable conditions gives rise to the resin 4, which is characterized bya chemically bound amide end group attached to a fragment of theoriginal polyester polymer P, designated as P₁, as well as to the lowermolecular weight polyester 5 designated as polymer P₂. Both P₁ and P₂ (4and 5) are lower molecular weight than the initial polyester P. Thecondensation reaction of the amine 3 with any of polyesters B, 4, or 5will continue until the amine has been substantially consumed. It issurprising that this high temperature reaction of a low melting orliquid amine, which will be a very low viscosity liquid, is capable ofmixing with the relatively high viscosity polyester melt. Further it isvery surprising that the reaction is quick enough to be substantiallyaccomplished in the very short contact time (0.5 to 3 minutes) in anormal melt extrusion process. Under most conditions, especially theshort contact time in an extruder, the initially formed amide will notreact further.

In the process of the present invention, the polyester is at leastpartially melted; that is, the polyester is at least 80 percent melted.More preferably, the polyester is at least 90 percent melted. Morepreferably, the polyester is at least 99 percent melted, and mostpreferably, the polyester is completely melted.

As indicated, the polyester, amine, and other optional components aremixed together. The process of mixing can be achieved using a mixer suchas a HENSCHEL-Mixer® high speed mixer or the like. Other low shearprocesses such as a drum tumbler, paint shaker, vee-blender or handmixing can also accomplish this mixing. Optionally some of theingredients can be pre-extruded with the polyester prior to amineaddition.

In one embodiment the polyester, amine, and optional additives are mixedand melted using an extruder or other melt mixing apparatus. In oneinstance the mixture is fed into the throat of an extruder via a hopperor loss in weight feeder. Alternatively, one or more of the componentscan be incorporated into the composition by feeding directly into theextruder at the throat and or downstream through a side feeder.Alternatively, any desired additives can also be compounded into amasterbatch and then combined with the remaining polymeric components atany point in the process. The extruder is generally operated at atemperature higher than that necessary to cause the composition to flow.Usually this is 20 to 50° C. above the polyester crystalline meltingpoint (Tm) The extrudate is quenched in a water batch and pelletized.Such pellets can be used for subsequent molding, shaping, or forming.

The extruder may be a twin screw extruder such as a Werner Pfleiderertwin screw extruder set at approximately 300 rpm using a 2 or 4-holedie. The barrel temperature is typically set in the range of 200 to 350°C., and more typically in the range of 230 to 270° C. The co-rotatingtwin screw extruder is run at ambient pressure without vacuum applied tothe vent. The absence of applied vacuum aids in the retention of theamine in the molten polymer of formula A allowing for a betteropportunity to chemically react to form a grafted amide functionality(3). In one instance the extrudate may then be cooled in a water bath,blown dry with air and chopped into pellets approximately ⅛ inch long.The continuous melt reaction may also be accomplished in single screwextruders under similar conditions.

In other instances the amine modification of the polyester resin may beaccomplished in an injection molding machine to tailor melt viscosity ofthe polyesters or polyester blends to the requirements of a specificpart or mold. In yet other instances the amine modification may beaccomplished in an extruder to make sheet, film or fibers.

The resulting resin of Formula 1 typically has a number averagemolecular weight of 10,000 to 30,000 and is characterized by acarboxylic acid (COOH) end group content of 10 meq/Kg or less. The resinis essentially free of metal cations or metal oxides selected from thegroup consisting of Pb, Hg, As, and Cd and thus contains 50 ppm or lessand more preferably 10 ppm or less of contaminants. In other instancesthese harmful metals are not detectable.

Another surprising benefits of some of the high flow resins made by theamine reaction is an improvement in the temperature at which they beginto form crystals when cooled from the melt (Tc=temperature ofcrystallization). The amine modified resins of Formula 2 have a Tc hatis higher than the Tc of the polyesters of Formula 1. In some instancesthe Tc of the modified resin is 1 to 10° C. greater than the Tc of theunmodified resin of Formula 1. A higher crystallization temperature is abenefit as it allows faster solidification of the molten polymer oftenleading to faster cycle time when molding parts, especially in aninjection molding processes. The resins of Formula 2 typically also havea higher heat of crystallization (dHc) as compared to the polyesters ofFormula 1. This may indicate a higher crystalline content which mayimprove stiffness and barrier properties of formed the polyesterarticle.

The resin of Formula 2 typically has an increased melt flow according toASTM D1238 that is at least 10 percent or higher compared to that of thepolyester of Formula 1. In other instances melt flow will be improved by50 percent over the starting resin. In other instances the aminemodified polyester will have a melt flow at 250° C. of from 20 to 100cc/10 min.

In other instances in addition to high melt flow the amine modifiedpolyester resins also have good stability in the melt (melt dwell)showing less than a 20% change in the initial melt viscosity after beingheld at 250° C. for 30 minutes at constant shear. In yet other instancesthe amine modified resin will show a change in melt viscosity (meltdwell) after 30 minutes of less than 15 percent of the initial value.With more than 0.5 wt % added amine the modified polyester shows achange in initial melt dwell viscosity of less than 10% of the initialvalue. This melt dwell stability is very significant in that it showsthat after the initial reaction of amine with the polyester of formula 1the reaction to form the higher flow polyester of formula 2 is complete.The small change in the melt dwell of the amine modified polyesters offormula 2 shows that there is no further reaction or degradation of themodified polyester. With higher amine content the resin show that inaddition to higher flow (a higher melt flow) there is also better meltstability (less change in melt dwell) than the starting polyester offormula 1.

Articles

The polyester composition of the invention may be formed by techniquesknown in the art. The ingredients are typically in powder or granularform, and extruded as a blend, and/or comminuted into pellets or othersuitable shapes. The ingredients may be combined in any manner, e.g., bydry mixing or by mixing in the melted state in an extruder, or in othermixers. For example, one embodiment comprises melt mixing theingredients in powder or granular form, extruding the mixture andcomminuting into pellets or other suitable shapes. Also included is drymixing the ingredients, followed by mixing in the melted state in anextruder.

The blends of the invention may be formed into shaped articles by avariety of common processes for shaping molten polymers such asinjection molding, compression molding, film or fiber extrusion and gasassist injection molding. Examples of such articles include electricalconnectors, enclosures for electrical equipment, automotive engineparts, lighting sockets and reflectors, electric motor parts, powerdistribution equipment, communication equipment, wire coatings and thelike including devices that have molded in snap fit connectors. Themodified polyester resins can also be made into fibers, films, andsheets.

The following examples illustrate, but do not limit the invention. Anyreferences cited herein are incorporated by reference in their entirety.

EXAMPLES

The materials used to prepare the amine-modified polyester resins aresummarized in Table 1.

TABLE 1 Materials PBT 315 Poly(1,4-butylene terephthalate), intrinsicviscosity (IV) = 1.10 dl/g, VALOX 315 from SABIC Innovative Plastics, 38meq/Kg COOH PBT 195 Poly(1,4-butylene terephthalate), intrinsicviscosity (IV) = 0.66 dl/g, VALOX 195 from SABIC Innovative Plastics, 17meq/Kg COOH PET Poly(1,2-ethylene terephthalate), intrinsic viscosity0.535 dl/g IV, 0.8% diethylene glycol (DEG), 20 meq/Kg COOH Glass FiberOwens Corning 183F, 13 micron diameter E glass C₁₈H₃₇NH₂ Octadecyl amine(also called stearyl amine) was AREEM 18D from Akzo Nobel, a distilledgrade, approximately 98.5% primary amine, Mw = 269.5, amine numberapproximately 208 mg KOH/g.

The blends were prepared by the extrusion of mixtures of polybutyleneterephthalate (PBT) or polyethylene terephthalate (PET) with octadecylamine and, in some instances, glass fiber (GF) as shown in Tables 2 to5. The ingredients were combined and mixed for approximately 4 minutesusing a paint shaker. The blends of Tables 2 to 5 were compounded on a30 mm Werner Pfleiderer twin screw extruder at approximately 450 to 520°F. (approximately 232 to 271° C.) barrel set temperature atapproximately 300 rpm using a 2 or 4-hole die. The blends were not driedprior to extrusion. The co-rotating twin screw extruder was run withoutvacuum applied to the vent. The melt was easy to strand and pelletize,and there was no foaming, vent flow or surging. The extrudate was cooledin a water bath, blown dry with air and then chopped into pelletsapproximately ⅛ inch long.

The fiber glass filled blends of Table 5 were mixed in a similar fashionadding the fiber glass after an initial mixing period of 4 minutes andgently mixing on a drum tumbler to prevent fuzzing of the glass fiberbundles. The blends were not dried prior to extrusion. The mixtures wereextruded on a 2.5 inch Prodex single screw extruder at 450 to 530° F.(approximately 232 to 277° C.) at 80 rpm using a double wave screw. Theextruder had a 6 hole die. No vacuum was applied to the vent. The meltwas easy to strand and pelletize, and there was no foaming, vent flow orsurging. The extrudate was cooled in a water bath, blown dry with airand then chopped into approximately ⅛ inch long pellets. The blends werenot dried prior to extrusion.

The pelletized extrudates were dried for at least 4 hours (h) at 120° C.and test parts were injection molded at a set temperature of 240 to 260°C. and mold temperature of approximately 100° C. using a 30 second cycletime.

Test Methods

Melt flow was run using a 1.26 or 2.16 Kg weight at 250 or 265° C. Thepellets had been dried for approximately 2 to 4 hours at 120° C. Themelt flow was measured after a 6 minute melt equilibration period and isreported as cubic centimeters (cc)/10 minutes according to ASTM D1238.

Weight average (Mw) and number average molecular weight (Mn) weremeasured by gel permeation chromatography (GPC) in a similar fashionaccording to ASTM D5296. GPC samples were prepared by dissolvingapproximately 40 mg of sample in 1 mL hexafluoro-2-propanol (HFIP) and 1mL chloroform. After complete dissolution, the polymer solution wasdiluted to 5% HFIP using chloroform. The GPC was run using 5% HFIP inchloroform as the eluent with a 295 nm UV detector. Polystyrene (PS)standards were used for calibration.

Differential scanning calorimetry (DSC) was performed according to ASTMD3418 with a 20° C. per minute heating rate to 250° C. for the PBTexamples and 290° C. for the PET examples and then cooled at −20° C. perminute. Temperature of crystallization (Tc) and heat of crystallization(dHc) was measured on first cool. The heat of crystallization (dHc),which is the energy released as crystals form from the molten polyester,is reported as Joules/gram (J/g). Temperature of melting (Tm) wasmeasured on second heat and is the peak melting point.

Melt dwell (time sweep) studies were performed according to ASTM D4440at 250° C. for 30 minutes under nitrogen on a rheometer with a sandwich,or parallel-plate/cone-plate, fixture. Viscosity data (poise=P) wascompared after 6 minutes (initial value) and 30 minutes (final value).The pellets were dried for approximately 2 to 4 hours at 120° C. priorto testing.

Flexural properties were measured on 3.2 mm injection molded barsaccording to ASTM method D790 with a 1.27 mm/min cross-head speed. Themolded samples were conditioned for at least 48 hours at 50 percentrelative humidity prior to testing.

In the data tables provided below, letters designate comparativeexamples while numbers designate examples of the invention.

Data

The results for the high molecular weight PBT examples are summarized inTable 2. From 0.1 to 1.0 weight percent of octadecyl amine was extrudedwith a high molecular weight PBT (315) in a twin screw extruder at 300rpm set at 450 to 510° F. (approximately 232 to 266° C.) with no vacuum.The melt flow values at 250° C. show that the addition of the aminevastly improves melt flow, giving a much higher melt flow compared toControl A, which contains no added amine. The flow improvement isespecially dramatic with 0.5 to 1.0 percent octadecyl amine, where themelt flow increased from 26.3 to 111, representing approximately atwo-fold to five fold increase in melt flow compared to Control A.Surprisingly, the octadecyl amine modified polyesters of Table 2 showedgood melt stability as measured by the change in viscosity (measured inpoise=P) between 6 and 30 minutes at 250° C. (melt dwell). With higheramine levels, the percent change in viscosity decreased from 16.5 to 0.6percent, indicative of improved melt stability with higher aminemodification.

TABLE 2 High MW PBT Examples Example A [Control] 1 2 3 4 5 WeightPercent PBT 315 100.0% 99.9% 99.7% 99.5% 99.3% 99.0% Weight PercentC₁₈H₃₇NH₂ 0.0% 0.1% 0.3% 0.5% 0.7% 1.0% Melt Flow 250° C., 2.16 Kg,cc/10 min. 14.4 16.2 26.3 40.2 58.2 111.0 Mw (PS stds) 95801 95404 8695882335 73618 67138 Mn 28042 28076 26467 25859 23974 22281 Melt dwell 250°C. 6 min. (P) 6905 6114 3678 2428 1701 972 Melt dwell 250° C. 30 min (P)5930 5104 3101 2166 1613 966 Percent change 6 to 30 min. −14.1% −16.5%−15.7% −10.8% −5.2% −0.6% T melting (Tm) ° C. 223.5 223.1 222.9 224.4224.0 224.7 T crystallization (Tc) ° C. 191.2 191.5 192.5 193.5 193.8193.9 Heat of cryst. (dHc) J/g 54.5 52.9 56.8 56.7 56.0 55.3

The high melt flow and favorable melt stability of the Examples in Table2 are an advantage for end-uses involving filling thin-walled moldedparts with high flow lengths. Examples 1 to 5 also showed enhancedcrystallization with increasing amine content as indicated by a highercrystallization temperature (Tc) and a higher heat of crystallization(dHc).

The results for the low molecular weight PBT examples are summarized inTable 3. In these runs, from 0.1 to 0.7 weight percent of octadecylamine was extruded with a low molecular weight PBT 195 in a twin screwextruder at 300 rpm set at 450 to 510° F. (approximately 230 to 265° C.)with no vacuum. As shown by the melt flow values at 250° C., theaddition of the amine vastly improved melt flow, giving a much highermelt flow compared to Example B which contains no added amine. Even whena lower weight was used for the melt flow (1.26 versus 2.16 Kg), themodified polyesters of Examples 6 to 9 still have exception flow. Theflow improvement is especially dramatic with 0.3 to 0.7 weight percentoctadecyl amine, where 0.7 weight percent of octadecyl amine representsa three-fold increase in melt flow as compared to Control B. Also ofnote is the higher crystallization temperature (Tc) and the increasedcrystallinity as shown by a higher heat of crystallization (dHc) ascompared to Example B.

TABLE 3 Low Mw PBT Examples Example B [Control] 6 7 8 9 Weight PercentPBT 195 100.0% 99.9% 99.7% 99.5% 99.3% Weight Percent C₁₈H₃₇NH₂ 0.0%0.1% 0.3% 0.5% 0.7% Melt Flow 250° C., 2.16 Kg, cc/10 min. 60.2 68.796.0 123.0 166.0 Mw (PS std) 55060 54302 53150 52378 51377 Mn 2077720506 20291 19922 19733 T melting (Tm) ° C. 223.6 224.2 223.8 223.8223.8 T crystallization (Tc) ° C. 195.4 197.6 198.8 197.6 196.9 Heat ofcryst. (dHc) J/g 57.7 57.9 58.4 60.8 62.0

Despite their relatively low molecular weights, the amine-modifiedresins of Table 3 can still be extruded and pelletized using normaloperating conditions, making this a very versatile process to achieve awide variety of viscosities in a simple, low cost, continuous, unitoperation.

The results for the PET examples are summarized in Table 4. With only0.3 to 1.0 weight percent octadecyl amine (Examples 10 to 13), PET meltflow at 265° C. was significantly increased over control (Control C). Inparticular, Example 13 represents a greater than four-fold increase inmelt flow as compared to Control C. The temperature of crystallization(Tc) was increased to 205 to 208° C., and the heat of crystallization(dHc) was increased from 44.5 J/g to as much as 53.9 J/g.

TABLE 4 PET Examples Examples C [Control] 10 11 12 13 Weight Percent PET100.0% 99.9% 99.7% 99.5% 99.3% Weight Percent C₁₈H₃₇NH₂ 0.0 0.3% 0.5%0.7% 1.0% Melt Flow 265° C., 1.2 Kg, cc/10 min. 50.8 94.3 101.2 137.5210.0 Mw 45577 40536 38284 36884 33834 Mn 16001 14699 14211 13900 13169T melting (Tm) ° C. 258.4 257.5 257.9 257.1 257.7 T crystallization (Tc)° C. 199.6 205.3 207.2 207.5 208.1 Heat of cryst. (dHc) J/g 44.5 49.451.0 53.9 53.1

The results for PBT examples that employed a glass fiber filler aresummarized in Table 5. These blends were prepared by adding the fiberglass after an initial mixing period of approximately 4 minutes and thengently mixing the mixture on a drum tumbler to prevent fuzzing of theglass fiber bundles. Examples 14 to 17 and Control D show the utility ofoctadecyl amine modification of 30 weight percent glass fiber (GF)reinforced PBT. With only 0.3 to 1.0 weight percent octadecyl amine,melt flow at 250° C. was increased from 4.6 to as high as 50.4 cc/10minute. The glass fiber and its chemical coating did not cause anyinterference in the reaction. Examples 14 to 17 all extruded well withno surging or foaming. The crystallization temperature (Tc) wasincreased as was the heat of crystallization (dHc). The change in meltviscosity on being held at 250° C. for 30 minutes was reduced with theadded octadecyl amine compared to the 30 percent GF control (Control D)which contained no amine. This finding indicates superior melt stabilityof the glass-reinforced high flow amine-modified resins. The flexuralmodulus was also increased in some instances to over 8000 MPa.

TABLE 5 Glass Filled High Mw PBT Examples Example D [Control] 14 15 1617 Weight Percent PBT 315 70.0% 69.7% 69.5% 69.3% 69.0% Weight PercentGlass Fiber 30.0% 30.0% 30.0% 30.0% 30.0% Weight Percent C₁₈H₃₇NH₂ 0.0%0.3% 0.5% 0.7% 1.0% Melt Flow 250° C., 2.16 Kg, cc/10 min 4.6 9.4 18.025.3 50.4 Mw (PS stds) 102200 84036 73638 65754 56692 Mn 29633 2593323606 21886 19820 Melt Dwell 250° C. 6 min. (P) 17992 9157 4577 37491722 Melt Dwell 250° C. 30 min. (P) 11621 6519 3716 2971 1628 Percentchange 6 to 30 min. −34.5% −28.8% −18.8% −20.7% −5.5% T melting (Tm) °C. 222.3 222.7 222.9 222.7 222.7 T crystallization (Tc) ° C. 189.3 191.6192.4 192.9 194.0 Heat of cryst. (dHc) J/g 38.9 39.4 42.0 39.4 45.2 FlexModulus MPa 7830 7880 8090 8350 8130 Flex Strength MPa 188 187 191 188183

The foregoing invention has been described in some detail by way ofillustration and example for purposes of clarity and understanding. Theinvention has been described with reference to various specificembodiments and techniques. However, it should be understood that manyvariations and modifications may be made while remaining within thespirit and scope of the invention. It will be obvious to one of skill inthe art that changes and modifications may be practiced within the scopeof the appended claims. Therefore, it is to be understood that the abovedescription is intended to be illustrative and not restrictive. Thescope of the invention should, therefore, be determined not withreference to the above description, but should instead be determinedwith reference to the following appended claims, along with the fullscope of equivalents to which such claims are entitled. All patents,patent applications, and publications cited in this application arehereby incorporated by reference in their entirety for all purposes tothe same extent as if each individual patent, patent application, orpublication were so individually denoted.

1. A solvent-free process for preparing an amine-modified thermoplasticpolyester resin comprising: mixing a melted polyester of Formula 1:

wherein: each T is independently a divalent C₆₋₁₀ aromatic group derivedfrom a dicarboxylic acid or a chemical equivalent thereof; each D isindependently a divalent C₂₋₈ alkylene group derived from a dihydroxycompound or a chemical equivalent thereof; and m is from 25 to 1000; anda melted amine, having the formula NHR¹R², wherein: R¹ is C₆₋₃₆ alkyl,R² is selected from the group consisting of hydrogen, C₁-C₃₆ alkyl,C₁-C₃₆ alkylene-aryl, C₁-C₃₆ alkylene-heteroaryl, C₁-C₃₆alkylene-cycloalkyl, C₁-C₃₆ alkylene-heterocycloalkyl, and NHR¹R²contains at least 10 carbons; thereby forming an amine-modifiedthermoplastic polyester resin characterized by one or both of thefollowing properties: (i) the resin comprises 0.01 to 5 weight percentof the amine; and (ii) the ratio of the melt flow of the resin comparedto the unmodified polyester of Formula 1, as measured according to ASTMD1238, is at least 1.05:1.
 2. The process of claim 1, wherein thepolyester is a linear polyester having repeating structural units ofFormula 1

and the resulting resin is a linear resin of Formula 2

wherein: each T is independently a divalent C₆₋₁₀ aromatic group derivedfrom a dicarboxylic acid or a chemical equivalent thereof; each D isindependently a divalent C₂₋₈ alkylene group derived from a dihydroxycompound or a chemical equivalent thereof; and m and n are each selectedfrom 25 to 1000 and n is less than m.
 3. The process of claim 2,wherein: each T in the resin of Formula 2 is independently phenyl ornaphthyl; and each D in the resin of Formula 2 is independently selectedfrom the group consisting of ethylene, propylene, butylene, anddimethylenecyclohexene.
 4. The process of claim 2, wherein the polyesterof Formula 1 is selected from the group consisting of poly(ethyleneterephthalate), poly(1,4-butylene terephthalate), poly(ethylenenaphthalate), poly(butylene naphthalate), poly(1,3-propyleneterephthalate), poly(cyclohexylenedimethylene terephthalate) andcombinations thereof.
 5. The process of claim 2, wherein the polyesterof Formula 1 is a post-consumer recycled polyester.
 6. The process ofclaim 2, wherein the polyester of Formula 1 further comprises 10 to 500ppm of one or more metal cations selected from the group consisting ofat least one of Ti, Sb, Sn, Zn, Ge, Zr, and Co.
 7. The process of claim2, wherein the polyester resin of Formula 2 is characterized by a —COOHend group content of 10 meq/kg or less.
 8. The process of claim 2,wherein the amine has a boiling point that is 200° C. or higher atambient pressure and a carbon to nitrogen ratio of 10:1 to 36:1.
 9. Theprocess of claim 2, wherein the resin of Formula 2 comprises 0.05 to 2.5weight percent of the reacted amine.
 10. The process of claim 2, whereinthe resin further comprises 1 to 60 weight percent of a filler selectedfrom the group consisting of fiber glass, carbon fibers, ceramic fibers,talc, clay, mica, wollastonite, silica, quartz, alumina, barium sulfate,carbon, graphite, metal oxides, glass beads, glass flakes, milled glass,and any combination thereof.
 11. The process of claim 10, comprising 10to 40 weight percent fiber glass with a diameter of 9 to 20 microns. 12.The process of claim 2, wherein 500 ppm or less of an organic solvent ispresent.
 13. The process of claim 2, wherein the process is a continuousprocess and wherein the blend comprising the polyester of Formula A andthe amine NHR¹R² are mixed in a single screw or twin screw extruder withno external vacuum applied.
 14. The process of claim 2, wherein mixingoccurs at a temperature in the range of 200° C. to 350° C.
 15. Theprocess of claim 2, wherein the resin of Formula 2 has a temperature ofcrystallization higher than the temperature of crystallization ofpolyester of Formula
 1. 16. The process of claim 2, the ratio of themelt flow of the resin of Formula 2 compared to the unmodified polyesterof Formula 1, as measured according to ASTM D1238, is at least 1.1:1.17. The process of claim 2, wherein the resin of Formula 2 has a meltviscosity at 250° C. of 20 to 100 cc/10 minute.
 18. The process of claim2, wherein 50 percent or more of the ester linkages in Formula 1 areterephthalate ester linkages.
 19. The process of claim 2, wherein theresin of Formula 2 is essentially free of metal cations or metal oxidesselected from the group consisting of Pb, Hg, As, and Cd.
 20. Anamine-modified polyester resin of Formula 2

prepared by the process of mixing a linear or branched polyester havingrepeating structural units of Formula 1

and an amine of formula NHR¹R² in an extruder, with no applied vacuumand a temperature of 200 to 350° C.; wherein: R¹ is C₆₋₃₆ alkyl R² isselected from the group consisting of hydrogen, C₁-C₃₆ alkyl, C₁-C₃₆alkylene-aryl, C₁-C₃₆ alkylene-heteroaryl, C₁-C₃₆ alkylene-cycloalkyl,C₁-C₃₆ alkylene-heterocycloalkyl, and NHR¹R² contains at least 10carbons; each T is independently a divalent C₆₋₁₀ aromatic group derivedfrom a dicarboxylic acid or a chemical equivalent thereof; each D isindependently a divalent C₂₋₈ alkylene group derived from a dihydroxycompound or a chemical equivalent thereof; m and n vary from 25 to 1000and n is less than m; and wherein the resin is characterized by one orboth of the following properties: (i) the resin comprises 0.01 to 5weight percent of the amine; and (ii) the ratio of the melt flow of theresin compared to the unmodified polyester of Formula 1, as measuredaccording to ASTM D1238, is at least 1.05:1.
 21. The resin prepared bythe process of claim 20, wherein the mixture further comprises 1 to 60weight percent of a filler selected from the group consisting of fiberglass, carbon fibers, ceramic fibers, talc, clay, mica, wollastonite,silica, quartz, alumina, barium sulfate, carbon, graphite, metal oxides,glass beads, glass flakes, milled glass, and any combination thereof.22. The resin prepared by the process of claim 20, wherein the filler is10 to 40 weight percent of a 9 to 20 micron diameter glass fiber.
 23. Anarticle comprising the composition prepared by the process of claim 1.24. The article of claim 23, wherein the article is an extruded film oran injection molded article.
 25. The article of claim 24 in the form ofa component for an electronic device.
 26. A method for forming anarticle, comprising shaping, extruding, blow molding, or injectionmolding a composition prepared by the process of claim 1.